In recent years, several types of speech recognition system adaptable to various kinds of electric equipments have been developed. For example, in a mobile telephone having a speech recognition function, a call origination may be made by voice activation in response to a user's utterance instead of manual dialing. The voice activated calling is accomplished by storing a set of feature parameters corresponding to a speech pattern associated with each party to be called and a corresponding telephone dial number when the system is in a speech registration mode, and by detecting correspondence between a speech pattern corresponding to a user's utterance made when the system is in a voice dialing mode and the stored speech patterns. In the event that one of the stored speech patterns matches with the speech pattern corresponding to the user's utterance made in the voice dialing mode, a call to a telephone dial number corresponding to the matched speech pattern is automatically made.
In such a conventional mobile telephone, however, it is possible that speech patterns which are being stored are similar with those which have previously been stored when more than one similar speech patterns are registered. Therefore, a wrong call due to misrecognition may be made. For example, if a speech pattern for "Tate" is registered with a corresponding telephone dial number, and a speech pattern "Kate" is registered with another corresponding telephone dial number, a call to the Tate's telephone dial number may be made in response to the user's utterance of "Kate". Therefore, in a conventional speech recognition system, misrecognition may occur as a result of registering several similar speech patterns.